The present invention relates to an organic electronic component comprising at least one organic layer between two electrodes, wherein the organic layer comprises at least one compound from the group of the BODIPYs proposed.
It is assumed that organic semiconductors based on low molecular weight or polymeric compounds will find increasing uses in many fields of the electrical industry. The advantages of organic chemistry are beneficial here, such as less energy-intensive processibility, better substrate compatibility and greater possible variation. Examples of organic electronics aside from general electronic circuits are OLEDs, OPVs, photodetectors and OFETs.
Organic electronic materials are usually divided into dopants and independent semiconductors. Dopants alter the electrical properties of a matrix layer when they are applied together therewith (for example coevaporated), but they need not be semiconductors themselves. The organic semiconductor materials, in contrast, are already semiconductive on their own. Organic semiconductors can fulfill various functions in an electronic component, for example charge transport, radiation absorption or radiation emission, it being possible for one or more functions to be fulfilled simultaneously.
Also additionally known are solar cells having organic active layers and a flexible configuration (Konarka—Power Plastic Series). The organic active layers may be formed from polymers (e.g. U.S. Pat. No. 7,825,326 B2) or small molecules (e.g. EP 2385556 A1). While it is a feature of polymers that they are not evaporable and can therefore only be applied from solutions, small molecules are evaporable.
The advantage of such organic-based components over the conventional inorganic-based components (semiconductors such as silicon, gallium arsenide) are the optical absorption coefficients, which are extremely high in some cases (up to 2×105 cm−1), and so it is possible to produce very thin solar cells with low material and energy expenditure. Further technological aspects are the low costs, the possibility of producing flexible large-area components on plastic films, and the virtually unlimited possible variations and unlimited availability of organic chemistry.
Organic solar cells consist of a sequence of thin layers (typically each of 1 nm to 1 μm in thickness) of organic materials which are preferably applied by vapor deposition under reduced pressure or spun on from a solution. Electrical contacts can be formed by metal layers, transparent conductive oxides (TCOs) and/or transparent conductive polymers (PEDOT-PSS, PANI).
A solar cell converts light energy to electrical energy. In this context, the term “photoactive” is understood to mean the conversion of light energy to electrical energy. In contrast to inorganic solar cells, the light does not directly generate free charge carriers in organic solar cells; instead, excitons are first formed, i.e. electrically uncharged excited states (bound electron-hole pairs). Only in a second step are these excitons separated into free charge carriers, which then contribute to electrical current flow.
In multiple solar cells, the individual stacked cells are usually connected in series, and so the cell that produces the lowest current limits the entire system. In order to be able to exploit the full solar spectrum, in contrast, several compounds are needed, which absorb at different wavelengths and can be combined in terms of energy.
Particularly for the field of nonpolymeric compounds, there are currently only few known IR absorbers in the range of 650-1400 nm for use in organic optoelectronics. IR absorbers are of particular interest since they absorb in the invisible region of light and therefore appear transparent to the human observer or, in combination with colored absorbers, can utilize a broader range of the solar spectrum.
WO 2006/111511 describes hexaarylene- and pentaarylenetetra-carboximides as active components in photovoltaics. WO2007/116001 relates to rylenetetracarboxylic acid derivatives and to the use thereof as organic n-type semiconductors for production of organic field-effect transistors and of solar cells. WO 2008/145172 relates to substituted carboxyphthalocyanines and to the use thereof as active component in photovoltaics.
WO2007/126052 describes a fluorescent compound based on a BODIPY base skeleton and use of the compounds described as fluorescent dyes. There is no description of the use of the BODIPYs described as a constituent in absorber or transport layers in semiconductive or optoelectronic components.
The IR dyes known from the prior art are not entirely satisfactory. For example, processibility is inadequate, they do not have thermal stability for evaporation under reduced pressure, they do not have satisfactory absorption intensity in thin layers (for example because of unsuitable preferential orientation in layer growth or too low a molar extinction coefficient), photostability is too low, they do not have adequate transport properties for utilization of radiation absorbed or they do not have a good energetic fit into the component.